The subject application relates to grey level calibration in a printing system. While the systems and methods described herein relate to grey level calibration, it will be appreciated that the described techniques may find application in other printing systems, other xerographic applications, and/or other scanning systems.
When calibrating print engine grey levels, a scanner illuminates a document and generates a photon count for the document (e.g., in reflection mode). Dark areas in the document have low or no L* values, which makes print engine calibration difficult at darker grey levels. Thus, when using a scanner as a measurement device in this manner, it is difficult to obtain good black/dark grey level information because of the low availability of measurable image bits in the dark end of the spectrum.
Marking device image calibration is often performed using an image quality analysis (IQA) routine, where a scanner is used to take two measurements from a printed page: the greyscale values of light and dark grey patches. Due to natural scanner properties, the measurement resolution of the dark grey patch is relatively poor (e.g., for an 8-bit scanner or the like).
Digitizing scanner data to a higher level of accuracy requires substantial increases in processing power and analog-to-digital converters, which is undesirably expensive and labor-intensive.
Accordingly, there is an unmet need for systems and/or methods that facilitate measuring grey levels at the low end of the spectrum for calibrating print engines and the like while overcoming the aforementioned deficiencies.